The disclosure of Japanese Patent Application No. HEI 10-233139 filed on Aug. 19, 1998 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
1. Field of the Invention
The present invention relates to a fuel amount detector.
2. Description of the Related Art
According to Japanese Patent Application No. HEI 9-5140, a fuel chamber is formed by a film in close contact with the surface of liquid fuel in a fuel tank and displaceable therewith, so as to reduce an amount of fuel vapor generated in the fuel tank. In this fuel tank, the amount of fuel in the fuel chamber is detected based on displacement of a portion of the film.
The aforementioned film has portions that are displaced differently depending on displacement of the surface of liquid fuel in the fuel tank. Thus, the portion of the aforementioned film for detecting an amount of fuel in the fuel chamber may not be displaced while another portion of the film may be deformed. In this case, it is impossible to precisely detect an amount of fuel in the fuel chamber. Especially in the case where the aforementioned fuel tank is installed in a moving body such as a vehicle, the film may be deformed in an unusual manner due to inclination, acceleration or deceleration of the vehicle. In this case, it is also impossible to precisely detect an amount of fuel in the fuel chamber.
It is an object of the present invention to precisely detect an amount of fuel in a fuel chamber of a fuel storage device having a plurality of portions that are displaceable differently according to an amount of fuel in the fuel chamber.
A fuel amount detector according to a first aspect of the present invention comprises a fuel storage device provided with a fuel chamber for storing fuel wherein the fuel chamber changes its volume in accordance with a change in an amount of fuel in the fuel chamber. In this fuel amount detector, at least two portions of a member forming the fuel chamber are displaceable in accordance with an amount of fuel in the fuel chamber, and the amount of fuel in the fuel chamber is detected based on displacement of the at least two portions. That is, the amount of fuel in the fuel chamber is detected based on displacement of the at least two portions, which are displaced in accordance with the amount of fuel in the fuel chamber.
In the aforementioned first aspect, the aforementioned two portions may be portions of a wall of the fuel chamber whose displacement directions and displacement amounts are different from each other.
Furthermore, in the first aspect, the fuel amount detector may include a position sensor for detecting relative displacement of the two portions. In this case, the fuel amount detector detects an amount of fuel in the fuel chamber based on the relative displacement of the two portions detected by the position sensor. In addition, the position sensor may be provided with a reference contact point abutting on one of the two portions and a detection contact point abutting on the other of the two portions. In this case, relative displacement of the two portions is detected based on a position of the detection contact point with respect to the reference contact point.
In the aforementioned first aspect, the fuel chamber may be provided with upper and lower walls that are displaced independent of each other in accordance with a change in an amount of fuel in the fuel chamber. In this case, the two portions constitute parts of the upper and lower walls.
In a second aspect of the present invention, the following features are added to the first aspect of the present invention. That is, the fuel chamber is formed of polygonal walls opposed to each other and side walls connecting end portions of the polygonal walls to each other. The polygonal walls and the side walls are deformable in accordance with a change in amount of fuel in the fuel chamber. The amount of fuel in the fuel chamber is detected based on displacement of the polygonal walls or the side walls in the fuel storage device resulting from deformation of the polygonal walls or the side walls. Namely, the amount of fuel is detected based on displacement of the two portions of the polygonal walls or the side walls that are displaced in accordance with the amount of fuel in the fuel chamber. Thus, the polygonal walls and the side walls constituting the fuel chamber are displaced substantially in a constant direction in accordance with an amount of fuel in the fuel chamber. Hence, displacement of the polygonal walls and the side walls can be detected precisely, so that the amount of fuel in the fuel chamber can be detected precisely.
In the aforementioned second aspect, the fuel chamber may have a generally rectangular parallelepiped shape. In this case, the polygonal walls opposed to each other constitute the upper and lower walls of the fuel chamber, and the fuel amount detector detects an amount of fuel in the fuel chamber based on displacement of the upper and lower walls of the fuel chamber.
In a third aspect of the present invention, the following features are added to the first aspect of the present invention. That is, an extendable member is disposed in the fuel chamber. A section of the extendable member is attached to one of the at least two portions and another section of the extendable member is attached to the other of the at least two portions, and an amount of fuel in the fuel chamber is detected based on relative displacement between the sections of the extendable member that are attached to the two portions respectively. Namely, the amount of fuel in the fuel chamber is detected by the extendable member disposed therein.
In a fourth aspect of the present invention, there is provided a fuel amount detector including a fuel storage device that is provided with a fuel chamber for storing fuel, the fuel chamber changing its volume in accordance with a change in amount of fuel in the fuel chamber. In this fuel storage device, an extendable member is disposed in the fuel chamber, and a float member floating on fuel in the fuel chamber is attached to a portion of the extendable member. A portion of the extendable member that is located below the float member is attached to a portion of a member forming the fuel chamber. An amount of fuel in the fuel chamber is detected based on relative displacement between the float member and the portion of the extendable member that is attached to the portion of the member forming the fuel chamber. Therefore, the float member floats on the surface of liquid fuel in the fuel chamber.
According to the first through fourth aspects of the present invention, even when one of the at least two portions is displaced much more greatly than the other, it is possible to precisely detect an amount of fuel in the fuel chamber.
According to the third and fourth aspects of the present invention, the amount of fuel in the fuel chamber is detected using the extendable member disposed therein. Therefore, means for detecting an amount of fuel in the fuel chamber need not be disposed outside the fuel chamber, whereby the fuel storage device becomes compact. Since the aforementioned member is extendable, it does not prevent the fuel chamber from changing its inner volume.
According to the fourth aspect of the present invention, the float member floats on the surface of liquid fuel in the fuel chamber. Thus, the present invention makes it possible to precisely detect an amount of fuel in the fuel chamber even when the surface of liquid fuel is formed therein.
In a fifth aspect of the present invention, there is provided a fuel amount detector including a fuel storage device that is provided with a fuel chamber whose inner volume changes in accordance with an amount of fuel stored therein and an auxiliary fuel chamber whose inner volume does not change in accordance with an amount of fuel stored therein. The auxiliary fuel chamber is connected to a lower area of the fuel chamber. In this fuel amount detector, an amount of fuel in the fuel chamber is detected based on a change in level of the surface of liquid fuel in the auxiliary fuel chamber, which changes according to an amount of fuel in the fuel chamber. Namely, the amount of fuel is detected based on displacement of the surface of liquid fuel formed in the auxiliary chamber whose inner volume does not change in accordance with an amount of fuel stored therein.
In the fifth aspect of the present invention, the fuel amount detector may include a float for detecting a level of the surface of liquid fuel in the auxiliary fuel chamber. In this case, the fuel amount detector detects an amount of fuel in the fuel chamber based on a level of the surface of liquid fuel in the auxiliary fuel chamber detected by the float.
In a sixth aspect of the present invention, the following features are added to the fifth aspect of the present invention. That is, an amount of fuel in the fuel chamber is detected based on a pressure in the auxiliary fuel chamber that changes in accordance with a change of the surface of liquid fuel in the auxiliary fuel chamber. Namely, the amount of fuel in the fuel chamber is detected based on a change of pressure in the auxiliary fuel chamber, whose inner volume does not change in accordance with a change in fuel amount in the fuel chamber.
According to the fifth and sixth aspects of the present invention, the amount of fuel in the fuel chamber is detected based on displacement of a surface of liquid fuel formed in the auxiliary fuel chamber whose volume does not change in accordance with an amount of fuel stored. Since the inner volume of the fuel chamber changes in accordance with the amount of fuel in the fuel chamber, there is no surface of liquid fuel formed in the fuel chamber. Thus, the amount of fuel in the fuel chamber cannot be detected based on the surface of liquid fuel therein. However, the present invention makes it possible to detect an amount of fuel in the fuel chamber based on a surface of liquid fuel in the auxiliary fuel chamber that is connected to the fuel chamber and displaced in accordance with an amount of fuel therein.
In the aforementioned sixth aspect, the fuel amount detector may further include a pressure sensor for detecting a pressure in the fuel chamber. Furthermore, the auxiliary fuel chamber may be provided with a gas storage portion that communicates with the auxiliary fuel chamber. In this case, the pressure sensor detects a pressure of gas in the gas storage portion, and the fuel amount detector detects an amount of fuel in the fuel chamber based on a pressure of gas in the gas storage portion that is detected by the pressure sensor.
In the aforementioned aspect of the present invention, the auxiliary fuel chamber may be provided with a gas discharging pipe through which gas is discharged from the auxiliary fuel chamber. In this case, an opening end of the gas discharging pipe on the side of the auxiliary fuel chamber terminates at a location lower than the upper wall of the auxiliary fuel chamber.
In the aforementioned aspect of the present invention, the auxiliary fuel chamber may be provided with a gas discharging pipe through which gas is discharged from the auxiliary fuel chamber. In this case, an opening end of the gas discharging pipe on the side of the auxiliary fuel chamber terminates at a location corresponding to the upper wall of the auxiliary fuel chamber. The pressure sensor is provided with a pressure sampling pipe that extends further below from the upper wall of the auxiliary fuel chamber and detects a pressure of gas stored in the pressure sampling pipe. The fuel amount detector detects an amount of fuel in the fuel chamber based on a pressure of gas detected by the pressure sensor.
According to a seventh aspect of the present invention, there is provided a fuel amount detector including a fuel storage device that is provided with a fuel chamber for storing fuel. The fuel chamber changes its volume in accordance with an amount of fuel in the fuel chamber. The fuel amount detector further includes a fuel supplying pipe that communicates with the fuel chamber and serves to fill the fuel chamber with fuel, and a liquid surface sensor for detecting a level of the surface of liquid fuel in the fuel supplying pipe. In this fuel amount detector, an amount of fuel in the fuel chamber is detected based on a level of the surface of liquid fuel in the fuel supplying pipe detected by the liquid surface sensor.